模板引擎，原来用jsp现在使用thymeleaf

01 导入依赖

使用thyme leaf需要先导入依赖
https://docs.spring.io/spring-boot/docs/2.1.6.RELEASE/reference/htmlsingle/#using-boot-starter
https://www.thymeleaf.org/
https://github.com/thymeleaf/thymeleaf
在SpringBoot中找到和thyme leaf相关的依赖

https://github.com/spring-projects/spring-boot/tree/v2.1.6.RELEASE/spring-boot-project/spring-boot-starters/spring-boot-starter-thymeleaf/pom.xml

<dependency>
	<groupId>org.thymeleaf</groupId>
	<artifactId>thymeleaf-spring5</artifactId>
</dependency>
<dependency>
	<groupId>org.thymeleaf.extras</groupId>
	<artifactId>thymeleaf-extras-java8time</artifactId>
</dependency>

导入到pom.xml中

或者是直接导入

<dependency>  
    <groupId>org.springframework.boot</groupId>  
    <artifactId>spring-boot-starter-thymeleaf</artifactId>  
</dependency>

idea中使用ctrl+N全局查询

导入后查找thymeleaf.properties类，跳转

public class ThymeleafProperties {  
    private static final Charset DEFAULT_ENCODING;  
    public static final String DEFAULT_PREFIX = "classpath:/templates/";  
    public static final String DEFAULT_SUFFIX = ".html";

约定目录为/templates ，文件后缀为html

测试一下，创建一个html文件名为test。

在此处为什么不说创建一个test.html文件呢？因为thymeleaf会识别到创建html文件但无法直接识别后缀为html的文件，假设直接创建test.html，则没有补全。

templates/test.html文件

<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
</head>  
<body>  
<h1>test</h1>  
<!--加上了<h1>标签，假设模板生效则字号为h1，无效则为正文字号-->  
</body>  
</html>

src\main\java\org\example\demo7\controller\testController.java文件

package org.example.demo7.controller;  
  
import org.springframework.stereotype.Controller;  
import org.springframework.web.bind.annotation.GetMapping;  
//import org.springframework.web.bind.annotation.RequestMapping;  
//import org.springframework.web.bind.annotation.ResponseBody;  
//import org.springframework.web.bind.annotation.RestController;  
  
@Controller  
//@RequestMapping("/hello")  
public class helloController {  
    @GetMapping("/test")  
//    @ResponseBody  
    // 使用@ResponseBody会直接输出return的内容  
    public String test() {  
        return "test";  
    }  
}

访问text路由，发现输出为h1样式，模板渲染成功

02 using

官方使用文档
https://www.thymeleaf.org/doc/tutorials/3.1/usingthymeleaf.html

按照使用文档的说明，导入约束

有命名空间就可以使用其相关语法了。我们直接去看语法

Simple expressions:
- Variable Expressions: ${...}
- Selection Variable Expressions: *{...}
- Message Expressions: #{...}
- Link URL Expressions: @{...}
- Fragment Expressions: ~{...}
Literals
- Text literals: 'one text', 'Another one!',…
- Number literals: 0, 34, 3.0, 12.3,…
- Boolean literals: true, false
- Null literal: null
- Literal tokens: one, sometext, main,…
Text operations:
- String concatenation: +
- Literal substitutions: |The name is ${name}|
Arithmetic operations:
- Binary operators: +, -, *, /, %
- Minus sign (unary operator): -
Boolean operations:
- Binary operators: and, or
- Boolean negation (unary operator): !, not
Comparisons and equality:
- Comparators: >, <, >=, <= (gt, lt, ge, le)
- Equality operators: ==, != (eq, ne)
Conditional operators:
- If-then: (if) ? (then)
- If-then-else: (if) ? (then) : (else)
- Default: (value) ?: (defaultvalue)
Special tokens:
- No-Operation: _

写个demo

所有的html元素都可以被thymeleaf替换接管： th:html元素

/templates/test.html文件

<!DOCTYPE html>  
<html lang="en" xmlns:th="http://www.thymeleaf.org">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
</head>  
<body>  
<div th:text="${msg}"></div>  
</body>  
</html>

src\main\java\org\example\demo7\controller\testController.java文件

package org.example.demo7.controller;  
import org.springframework.ui.Model;  
//import ch.qos.logback.core.model.Model;  
import org.springframework.stereotype.Controller;  
import org.springframework.web.bind.annotation.RequestMapping;  
  
@Controller  
public class helloController {  
    @RequestMapping("/test")  
    public String test(Model model) {  
        model.addAttribute("msg","springBoot");  
        return "test";  
    }  
}

注意model中可能存在没有addAttribute方法的问题，注意一下model依赖是否正确。是import org.springframework.ui.Model;

运行一下，成功打印。

测一下其他

是否转义
/templates/test.html文件

<!DOCTYPE html>  
<html lang="en" xmlns:th="http://www.thymeleaf.org">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
</head>  
<body>  
<div th:text="${msg}"></div>  
<div th:utext="${msg}"></div>  
</body>  
</html>

src\main\java\org\example\demo7\controller\testController.java文件

package org.example.demo7.controller;  
import org.springframework.ui.Model;  
//import ch.qos.logback.core.model.Model;  
import org.springframework.stereotype.Controller;  
import org.springframework.web.bind.annotation.RequestMapping;  
  
@Controller  
public class helloController {  
    @RequestMapping("/test")  
    public String test(Model model) {  
        model.addAttribute("msg","<h1>springBoot</h1>");  
        return "test";  
    }  
}

数组遍历
/templates/test.html文件

<!DOCTYPE html>  
<html lang="en" xmlns:th="http://www.thymeleaf.org">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
</head>  
<body>  
<div th:text="${msg}"></div>  
<div th:utext="${msg}"></div>  
  
<div th:each="user:${users}" th:text="${user}"></div>  
</body>  
</html>

src\main\java\org\example\demo7\controller\testController.java文件

package org.example.demo7.controller;  
import org.springframework.ui.Model;  
//import ch.qos.logback.core.model.Model;  
import org.springframework.stereotype.Controller;  
import org.springframework.web.bind.annotation.RequestMapping;  
  
import java.util.Arrays;  
  
@Controller  
public class helloController {  
    @RequestMapping("/test")  
    public String test(Model model) {  
        model.addAttribute("msg","<h1>springBoot</h1>");  
  
        model.addAttribute("users", Arrays.asList("symya1","symya2","symya3"));  
  
        return "test";  
    }  
}

等等跟着用就完事了，跟vue很像